1. Field
The disclosed technology relates to an image forming apparatus and a waste toner warning method and, more specifically, to an image forming apparatus and a waste toner warning method which are adapted to detect the amount of waste toner accumulated in a waste toner storing section and/or to provide a warning on the basis of the detection.
2. Description of the Related Art
Image forming apparatuses are conventionally known which are adapted to output an image by forming an electrostatic latent image on an image carrier, then developing the electrostatic latent image into a toner image with a toner, and transferring the toner image onto a recording medium. One example of such image forming apparatuses is an electrophotographic multifunction peripheral. In the image forming apparatus, the toner slightly remains on the image carrier after the toner image is transferred onto the recording medium. Therefore, the remaining toner is removed in a cleaning section before the next electrostatic latent image is formed on the image carrier. The removed toner is electrically charged, and contaminated with paper dust and the like. This makes it impossible to reuse the toner. Therefore, the removed toner is stored as a waste toner in a dedicated container and, before the container is filled to capacity, the waste toner stored in the container is discarded. Further, the container is typically detachable for replacement, so that the waste toner can be easily discarded with the container.
The amount of the waste toner to be removed is dependent upon the patterns and sizes of images to be formed and the state of the image carrier. Therefore, a detection mechanism is typically provided for detecting the full capacity state of the waste toner container. A conventionally known example of the detection mechanism is adapted to detect the weight of the container in which the waste toner is accumulated and, when the weight of the container reaches a predetermined level, provides a warning for prompting a user to discard the waste toner (see, for example, Japanese Unexamined Patent Publication No. HEI09(1998)-212052).
In a conventional waste toner detection method and a warning method based on the waste toner detection method, the discard of the waste toner is requested in the following manner when the full capacity state of the waste toner container is detected during a sequence of printing jobs. For example, the printing job sequence is interrupted to request the discard of the waste toner after a current printing job is completed. Alternatively, the discard of the waste toner is requested after the printing job sequence is completed. In a so-called high speed image forming apparatus adapted for a large volume printing process, however, a great number of pages might be printed before the completion of the printing job sequence after the detection of the full capacity state of the waste toner container. To cope with such a case, a greater margin may be provided for the detection of the full capacity state of the waste toner container. However, if small volume printing jobs are sequentially performed, the warning is provided even with the waste toner container having a sufficient residual capacity for storing the waste toner. On the other hand, the high speed image forming apparatus, which is expected to efficiently perform the printing process, is increasingly required to avoid the interruption of the job sequence as much as possible for reduction of downtime. In this connection, it is unreasonable to interrupt the job sequence for the discard of the waste toner, so that the replacement of the container is requested before the start of the job sequence.
Further, the waste toner container for the high speed image forming apparatus has a greater volume for reducing the frequency of the discard of the waste toner. For example, the container is capable of storing about 5 kg of waste toner in the full capacity state. Where the conventional detection mechanism adapted to detect the weight is employed for the high speed image forming apparatus, the greater capacity container suffers from a greater detection error than a smaller capacity container.
For the reduction of the downtime, the image forming apparatus is required to provide the warning for requesting the discard of the waste toner when the user performs any other operation on the image forming apparatus.
Hence, there is a demand for a method for predicting the full capacity state of the waste toner container so as to avoid the interruption of the printing job sequence, a method for accurately detecting the full capacity state of the waste toner container for the reduction of the frequency of the discard of the waste toner, and/or a detection method which makes it possible to provide a warning for the reduction of the downtime.